Combining application and data tiers on different platforms to create workload distribution recommendations

ABSTRACT

A method, apparatus and computer program product for improved load balancing provides for the grouping under a same workload of both application instances in an application tier, and data sharing members in a data tier. This grouping enables a workload manager to make recommendations (to load balancer appliances) about how to distribute workload connections, e.g., based on metrics gathered from both the application and data tiers. In this approach, both applications and data sources are grouped into a workload grouping, and health, status and capacity information about both of these tiers (application and data) is then used to determine an overall distribution policy for the workload. These different tiers can reside on the same or different operating system environments.

BACKGROUND OF THE INVENTION Technical Field

This disclosure relates generally to data processing systems and, inparticular to managing requests received from clients. Still moreparticularly, the disclosure relates to load balancing and managingrequests from clients.

Background of the Related Art

Workload load balancing is a technique to distribute TCP/IP-basedworkload requests (connections) across similar server applications toachieve optimal resource utilization, maximize throughput, minimizeresponse time, and to avoid overloading server applications or systems.By using multiple server applications (instead of a single serverapplication) with load balancing, one can increase reliability throughredundancy. The load balancing service usually is provided by adedicated software program or hardware device. A workload managerprovides distribution recommendations to the load balancing service(i.e. a load balancer appliance).

In workload management environments of this type, server applicationsthat access the same data sources typically are included in the sameworkload. This allows monitoring agents to verify that all of theseapplications are available and able to handle additional connections onbehalf of the workload. It also enables a workload manager to have aconsolidated view of the applications in the workload, thereby enablingeasy switching of the workloads between geographically separated sites(i.e., different clusters of systems). In particular, the workloadmanager can signal a load balancer appliance that all connections to theserver applications making up the workload are to be switched at thesame time to the alternate site. This ensures that access by theapplications to the data sources is only done from one site at any pointin time.

Many customers with mainframe applications either have combined theapplication and data tier on the same platform (i.e., the same operatingsystem), while others have migrated their application tier to lower costplatforms while preserving their investment in the data tier (by leavingit on its existing platform). For example, most customers continue tomaintain their business critical data on the mainframe (e.g., IBM® z/OS)systems, relying on their strength of high availability and security oftheir data tier. But, such customers also are writing new businessapplications that are hosted on a different platform, for example,web-based applications within an application server running on IBM Linuxon System z. This application tier accesses the data tier residing onthe mainframe. As such, such customers have two different platforms tomonitor to determine the availability of a workload on a site or whichsite is best able to handle additional workload connections.

BRIEF SUMMARY

Generally, this disclosure describes a workload request load balancingmethod, apparatus and computer program product that provides for thegrouping under a same workload of application tiers and data tiers, evenwhen those tiers reside on different platforms. This grouping enables aworkload manager to make recommendations (to load balancer appliances)about how to distribute workload connections, e.g., based on metricsgathered from both the application and data tiers.

According to this disclosure, a workload manager in a site uses health,availability and capacity of the applications in the site's applicationtier as well as the number of application instances in the site as partof their calculations to determine how to route a workload's connectionsacross two sites. The metrics used to make this decision are collectedby application tier monitoring agents, which pass the information to theworkload manager. In addition, the workload manager receives informationregarding the health, availability and capacity of one or more datasharing members in the site's data tier, as well as the number of datasharing members in the site as additional information for theircalculations to determine how to route a workload's connections acrosstwo sites. These metrics are collected by data tier monitoring agents,which pass the information to the workload manager. The workload manageruses these metrics, as well as learning the number of applicationinstances and data sharing members within a site, to determine adistribution policy (or recommendation) of the workload across bothsites. This recommendation is provided to one or more load balancerappliances, which then use the distribution recommendation to directrequests to the site, or to an alternate site.

Thus, according to this approach both applications and data sources aregrouped into a workload grouping, and information about both of thesetiers (application and data) is then used to determine a distributionpolicy for the workload. These different tiers can reside on the same ordifferent operating system environments.

The foregoing has outlined some of the more pertinent features of thedisclosed subject matter. These features should be construed to bemerely illustrative. Many other beneficial results can be attained byapplying the disclosed subject matter in a different manner or bymodifying the subject matter as will be described.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the subject matter and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIG. 1 depicts an exemplary block diagram of a distributed dataprocessing environment in which exemplary aspects of the illustrativeembodiments may be implemented;

FIG. 2 is an exemplary block diagram of a data processing system inwhich exemplary aspects of the illustrative embodiments may beimplemented;

FIG. 3 illustrates a workload management environment;

FIG. 4 illustrates how a known multi-site workload management system isused to load balance TCP/IP workload;

FIG. 5 illustrates the basic method of this disclosure whereinapplications and data sources are grouped and monitored as a singleworkload; and

FIG. 6 illustrates the subject matter of this disclosure, wherein bothapplications and data sharing members are monitored and combined into asame workload, and load balancing decisions are made that affect bothtiers.

DETAILED DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT

With reference now to the drawings and in particular with reference toFIGS. 1-2, exemplary diagrams of data processing environments areprovided in which illustrative embodiments of the disclosure may beimplemented. It should be appreciated that FIGS. 1-2 are only exemplaryand are not intended to assert or imply any limitation with regard tothe environments in which aspects or embodiments of the disclosedsubject matter may be implemented. Many modifications to the depictedenvironments may be made without departing from the spirit and scope ofthe present invention.

Client-Server Technologies

With reference now to the drawings, FIG. 1 depicts a pictorialrepresentation of an exemplary distributed data processing system inwhich aspects of the illustrative embodiments may be implemented.Distributed data processing system 100 may include a network ofcomputers in which aspects of the illustrative embodiments may beimplemented. The distributed data processing system 100 contains atleast one network 102, which is the medium used to provide communicationlinks between various devices and computers connected together withindistributed data processing system 100. The network 102 may includeconnections, such as wire, wireless communication links, or fiber opticcables.

In the depicted example, server 104 and server 106 are connected tonetwork 102 along with storage unit 108. In addition, clients 110, 112,and 114 are also connected to network 102. These clients 110, 112, and114 may be, for example, personal computers, network computers, or thelike. In the depicted example, server 104 provides data, such as bootfiles, operating system images, and applications to the clients 110,112, and 114. Clients 110, 112, and 114 are clients to server 104 in thedepicted example. Distributed data processing system 100 may includeadditional servers, clients, and other devices not shown.

In the depicted example, distributed data processing system 100 is theInternet with network 102 representing a worldwide collection ofnetworks and gateways that use the Transmission ControlProtocol/Internet Protocol (TCP/IP) suite of protocols to communicatewith one another. At the heart of the Internet is a backbone ofhigh-speed data communication lines between major nodes or hostcomputers, consisting of thousands of commercial, governmental,educational and other computer systems that route data and messages. Ofcourse, the distributed data processing system 100 may also beimplemented to include a number of different types of networks, such asfor example, an intranet, a local area network (LAN), a wide areanetwork (WAN), or the like. As stated above, FIG. 1 is intended as anexample, not as an architectural limitation for different embodiments ofthe disclosed subject matter, and therefore, the particular elementsshown in FIG. 1 should not be considered limiting with regard to theenvironments in which the illustrative embodiments of the presentinvention may be implemented.

With reference now to FIG. 2, a block diagram of an exemplary dataprocessing system is shown in which aspects of the illustrativeembodiments may be implemented. Data processing system 200 is an exampleof a computer, such as client 110 in FIG. 1, in which computer usablecode or instructions implementing the processes for illustrativeembodiments of the disclosure may be located.

With reference now to FIG. 2, a block diagram of a data processingsystem is shown in which illustrative embodiments may be implemented.Data processing system 200 is an example of a computer, such as server104 or client 110 in FIG. 1, in which computer-usable program code orinstructions implementing the processes may be located for theillustrative embodiments. In this illustrative example, data processingsystem 200 includes communications fabric 202, which providescommunications between processor unit 204, memory 206, persistentstorage 208, communications unit 210, input/output (I/O) unit 212, anddisplay 214.

Processor unit 204 serves to execute instructions for software that maybe loaded into memory 206. Processor unit 204 may be a set of one ormore processors or may be a multi-processor core, depending on theparticular implementation. Further, processor unit 204 may beimplemented using one or more heterogeneous processor systems in which amain processor is present with secondary processors on a single chip. Asanother illustrative example, processor unit 204 may be a symmetricmulti-processor (SMP) system containing multiple processors of the sametype.

Memory 206 and persistent storage 208 are examples of storage devices. Astorage device is any piece of hardware that is capable of storinginformation either on a temporary basis and/or a permanent basis. Memory206, in these examples, may be, for example, a random access memory orany other suitable volatile or non-volatile storage device. Persistentstorage 208 may take various forms depending on the particularimplementation. For example, persistent storage 208 may contain one ormore components or devices. For example, persistent storage 208 may be ahard drive, a flash memory, a rewritable optical disk, a rewritablemagnetic tape, or some combination of the above. The media used bypersistent storage 208 also may be removable. For example, a removablehard drive may be used for persistent storage 208.

Communications unit 210, in these examples, provides for communicationswith other data processing systems or devices. In these examples,communications unit 210 is a network interface card. Communications unit210 may provide communications through the use of either or bothphysical and wireless communications links.

Input/output unit 212 allows for input and output of data with otherdevices that may be connected to data processing system 200. Forexample, input/output unit 212 may provide a connection for user inputthrough a keyboard and mouse. Further, input/output unit 212 may sendoutput to a printer. Display 214 provides a mechanism to displayinformation to a user.

Instructions for the operating system and applications or programs arelocated on persistent storage 208. These instructions may be loaded intomemory 206 for execution by processor unit 204. The processes of thedifferent embodiments may be performed by processor unit 204 usingcomputer implemented instructions, which may be located in a memory,such as memory 206. These instructions are referred to as program code,computer-usable program code, or computer-readable program code that maybe read and executed by a processor in processor unit 204. The programcode in the different embodiments may be embodied on different physicalor tangible computer-readable media, such as memory 206 or persistentstorage 208.

Program code 216 is located in a functional form on computer-readablemedia 218 that is selectively removable and may be loaded onto ortransferred to data processing system 200 for execution by processorunit 204. Program code 216 and computer-readable media 218 form computerprogram product 220 in these examples. In one example, computer-readablemedia 218 may be in a tangible form, such as, for example, an optical ormagnetic disc that is inserted or placed into a drive or other devicethat is part of persistent storage 208 for transfer onto a storagedevice, such as a hard drive that is part of persistent storage 208. Ina tangible form, computer-readable media 218 also may take the form of apersistent storage, such as a hard drive, a thumb drive, or a flashmemory that is connected to data processing system 200. The tangibleform of computer-readable media 218 is also referred to ascomputer-recordable storage media. In some instances,computer-recordable media 218 may not be removable.

Alternatively, program code 216 may be transferred to data processingsystem 200 from computer-readable media 218 through a communicationslink to communications unit 210 and/or through a connection toinput/output unit 212. The communications link and/or the connection maybe physical or wireless in the illustrative examples. Thecomputer-readable media also may take the form of non-tangible media,such as communications links or wireless transmissions containing theprogram code. The different components illustrated for data processingsystem 200 are not meant to provide architectural limitations to themanner in which different embodiments may be implemented. The differentillustrative embodiments may be implemented in a data processing systemincluding components in addition to or in place of those illustrated fordata processing system 200. Other components shown in FIG. 2 can bevaried from the illustrative examples shown. As one example, a storagedevice in data processing system 200 is any hardware apparatus that maystore data. Memory 206, persistent storage 208, and computer-readablemedia 218 are examples of storage devices in a tangible form.

In another example, a bus system may be used to implement communicationsfabric 202 and may be comprised of one or more buses, such as a systembus or an input/output bus. Of course, the bus system may be implementedusing any suitable type of architecture that provides for a transfer ofdata between different components or devices attached to the bus system.Additionally, a communications unit may include one or more devices usedto transmit and receive data, such as a modem or a network adapter.Further, a memory may be, for example, memory 206 or a cache such asfound in an interface and memory controller hub that may be present incommunications fabric 202.

Computer program code for carrying out operations of the presentinvention may be written in any combination of one or more programminglanguages, including an object-oriented programming language such asJava™, Smalltalk, C++, C#, Objective-C, or the like, and conventionalprocedural programming languages. The program code may execute entirelyon the user's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer, or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's computerthrough any type of network, including a local area network (LAN) or awide area network (WAN), or the connection may be made to an externalcomputer (for example, through the Internet using an Internet ServiceProvider).

Those of ordinary skill in the art will appreciate that the hardware inFIGS. 1-2 may vary depending on the implementation. Other internalhardware or peripheral devices, such as flash memory, equivalentnon-volatile memory, or optical disk drives and the like, may be used inaddition to or in place of the hardware depicted in FIGS. 1-2. Also, theprocesses of the illustrative embodiments may be applied to amultiprocessor data processing system, other than the SMP systemmentioned previously, without departing from the spirit and scope of thedisclosed subject matter.

As will be seen, the techniques described herein may operate inconjunction within the standard client-server paradigm such asillustrated in FIG. 1 in which client machines communicate with anInternet-accessible Web-based portal executing on a set of one or moremachines. End users operate Internet-connectable devices (e.g., desktopcomputers, notebook computers, Internet-enabled mobile devices, or thelike) that are capable of accessing and interacting with the portal.Typically, each client or server machine is a data processing systemsuch as illustrated in FIG. 2 comprising hardware and software, andthese entities communicate with one another over a network, such as theInternet, an intranet, an extranet, a private network, or any othercommunications medium or link. A data processing system typicallyincludes one or more processors, an operating system, one or moreapplications, and one or more utilities. The applications on the dataprocessing system provide native support for Web services including,without limitation, support for HTTP, SOAP, XML, WSDL, UDDI, and WSFL,among others. Information regarding SOAP, WSDL, UDDI and WSFL isavailable from the World Wide Web Consortium (W3C), which is responsiblefor developing and maintaining these standards; further informationregarding HTTP and XML is available from Internet Engineering Task Force(IETF). Familiarity with these standards is presumed.

Legacy Computer Systems

Mainframe computer systems are widely used for a variety of dataprocessing functions. For example, many corporate financial andaccounting systems were developed for, and operate on, mainframecomputing systems. Although the use of personal computers and personalcomputer networks has proliferated in recent years, mainframe computersystems, referred to as legacy systems, are expected to remain popularfor many types of data processing for years to come. A mainframecomputer system typically includes multiple user terminals connected toa mainframe host computer. Various software applications may be residenton, or accessible to, the host computer. The user terminals, which aresometimes referred to as client terminals or “clients,” communicate withthe mainframe host computer via a host communications system. The IBM3270 terminal system is one of the more widely-used systems forcommunicating with host computers. Typically, a 3270 terminal does nothave its own data processing capability. Instead, a 3270 terminal maydisplay screens generated by applications running on a host, and maycommunicate information from a user back to a host for processing. Auser interface of an IBM 3270 terminal system comprises a plurality ofscreens that are generated by host applications for display on the 3270terminal. Over the past few years, many 3270 terminals have beenreplaced with personal computers (PCs) configured to communicate withthe mainframe computer system via 3270 terminal emulation software.

In many applications, 3270 terminals, or other data processing devices(e.g., a PC) emulating a 3270 terminal, now access the host computer viathe Internet. For example, in systems operating under the TN3270Eprotocols, the 3270 terminals may access application software on a hostcomputer via a combination of a TCP/IP connection between the TN3270Eclient terminal and a TN3270E server, and via a Systems NetworkArchitecture (SNA) session between the TN3270E server and the SNAapplication software on the host mainframe computer.

It is also known to integrate client-server technologies with mainframecomputing environments. A representative multi-component system of thistype, wherein components work together cooperatively to form a largersystem, is the IBM® HyperText Transfer Protocol (HTTP) and Web Servicesprocessing environment, which may be implemented using IBM mainframecomputers, such as the IBM z196 family of computing machines. Thisenvironment typically includes IBM's WebSphere® Application Server (WAS)middleware platform software product, working in conjunction with one ormore transaction processing products, such as IBM Customer InformationControl System (CICS®) and/or IBM Information Management System (IMS), amessage processing product, such as IBM WebSphere MQ, and a relationaldatabase, such as the IBM DB2® database. An objective of amulti-component environment is to provide a high performance transactionprocessing computing system or environment accessible to clientend-users via Internet browsers using HTTP or other Web Services. Inthis environment, the client end-user making the HTTP or Web Servicesrequest communicates directly with the application server. Typically, tofulfill the transaction request from the distributed client end-user,the application server invokes the services of one or more othercomponents in the environment. One of more of these components typicallyexecute on an operating system, such as IBM z/OS® operating system,which is often referred to as a “mainframe” operating system platform.

Load Balancing Workload Groups

As further background, FIG. 3 illustrates a representative workloadmanagement environment 300 in which the techniques of this disclosuremay be implemented.

In this environment, client applications 302 run on client computers 304within or in association with the workload management environment 300.As depicted, client applications 302 generate requests 306 for services308. Services 308 may include, for example, at least one of retrieving afile, retrieving a webpage, writing data, downloading a program,deleting a file, and/or other suitable types of access. Requests 306 aresent over network 310 to server applications 312 on group of computersystems 314. Server applications 312 may be any applications configuredto process requests 306 to provide services 308. Server applications 312may be, for example, at least one of a database server, a file transferprotocol (FTP) server, a web server, a mail server, and/or othersuitable types of applications. In these illustrative examples, computersystems within group of computer systems 314 may be a computer, acomputer cluster, or other configurations of computer systems configuredto run server applications 312.

Workload manager 316 sends requests 306 to server applications 312.Workload manager 316 may be implemented using hardware, software, or acombination of the two. When implemented with hardware, workload manager316 takes the form of workload manager system 318. Workload managersystem 318 comprises hardware 320 and also may include software 322.When processor units are used in hardware 320, these processor units maybe located on the same or different computers.

Workload manager 316 is configured to balance workloads 324 in group ofcomputer systems 314. Workloads 324 are balanced by the manner in whichworkload manager 316 distributes requests 306 to server applications 312running on group of computer systems 314. Workload manager 316 may beimplemented in a number of different ways. For example, workload manager316 may include load balancing processes and may directly distributerequests 306 to server applications 312. Alternatively, workload manager316 may make recommendations for the distribution of requests 306. Theserecommendations may then be used by a load balancer implemented as aseparate component to distribute requests 306 to server applications312.

Server applications 312 may access common resources 326 when processingrequests 306. Common resources 326 may include data sources, storagesystems, processor systems, routing systems, and/or other suitable typesof resources. Resources may take the form of hardware, data, software,or other suitable forms. A common resource within common resources 326is a resource that is used by two or more server applications withinserver applications 312.

Workload manager 316 identifies which of server applications 312 receiveparticular requests from requests 306 based on common resources 326 usedby server applications 312. Workload manager 316 may be implemented invarious devices. For example, workload manager 316 may be implemented ina switch, a domain name server, and/or other suitable types of hardwaredevices. In these illustrative examples, workload manager 316 selects aserver application within server applications 312 to process a requestin requests 306 based on group information 328 and policy 330. Groupinformation 328, in these examples, is groupings of server applications312. For example, group information 328 comprises set of workload groups332. Set of workload groups 332 is comprised of server applicationgroups 334. Each workload group in set of workload groups 332 has two ormore server application groups from server application groups 334. Inaddition, weights 335 may be associated with server application groups334. In other words, each server application in a server applicationgroup may have one or more weights. Additionally, each serverapplication group also may be assigned one or more weights. Weights 335are used with policy 330.

Policy 330 is one or more rules for determining which of serverapplications 312 receive particular requests in requests 306. Policy 330may include rules for assigning requests 306 based on common resources326. Weights 335 may be applied to policy 330 in assigning requests 306based on common resources 326. For example, a rule in policy 330 may beto assign all requests to server applications 312 that use a particularcommon resource. For example, the common resource may be a computersystem in group of computer systems 314. As another example, whenaccessing data sources, two data sources may be copies of each other inwhich different server applications in server applications 312 areassigned to each of the copies of the data source. These data sourcesmay be synchronized or updated at some point so that the copies areidentical. With this type of resource, policy 330 may include a rulethat states that access to a particular cell, record, entry, table, orother portion of a data source are all made to the same copy.

Typically, workload manager 316 performs load balancing for a workloadgroup. Each server application group has one or more serverapplications. Typically, load balancing is performed with respect to aserver application group. In the illustrative examples, workload manager316 is further configured to provide load balancing based on workloadgroups. For example, workload group 325 in set of workload groups 332includes server application group 338 and server application group 340.Some of the server applications in server application group 338 may runon the same computer system as some of the server applications in serverapplication group 340. This is one example of a use of common resources326. As another example, some of the server applications in serverapplication group 338 may access the same data sources as some of theserver applications in server application group 340. This access to dataresources is another example of common resources 326.

By load balancing using server applications from server applicationgroup 338 and server application group 340 that use common resources326, improved performance may occur. For example, if common resources326 include data sources 342 that are synchronized between differentserver applications in server application group 338 and serverapplication group 340, distributing the requests to server applicationsthat use the same data source may reduce conflicts between data sources342 when these data sources are replicated.

In these illustrative examples, server applications in serverapplication group 338 and server application group 340 that use the samedata source in data sources 342 are considered to be on the samecomputer system. As a result, server applications in the same clusterthat end up in different server groups may be taken into account in loadbalancing when those server groups are put together into a workloadgroup. Workload manager 316 may use the mapping of server applicationgroups into a workload group to provide better load balancing withrespect to distributing requests to server applications 312 that usecommon resources 326 as compared to load balancing just within a serverapplication group.

Workload manager 316 also may identify performance parameters 344generated during processing of requests 306. Performance parameters 344are any values that relate to the use of resources to process requests306. These resources may include common resources 326. Results fromanalyzing performance parameters 344 may be used to identifyinefficiencies in accessing common resources 326. The result may be usedto modify group information 328. Inefficiencies may include, forexample, without limitation, conflicts in data, a larger than desirednumber of locks for data, data access requiring more time than desired,under use of a hardware resource, and other inefficiencies.

The modification of group information 328 may include adding a workloadgroup, changing server application groups within a workload group,deleting a workload group, and/or other suitable modifications. Further,changing values for weights 335 in policy 330 also may occur using theresults from the analysis of performance parameters 344.

The illustration of workload management environment 300 in FIG. 3 is notmeant to imply physical or architectural limitations to the manner inwhich different illustrative embodiments may be implemented. Othercomponents in addition to and/or in place of the ones illustrated may beused. Some components may be unnecessary. Also, the blocks are presentedto illustrate some functional components. One or more of these blocksmay be combined and/or divided into different blocks when implemented inan illustrative embodiment. For example, in some illustrative examples,additional workload managers, in addition to workload manager 316, maybe present within network 310. For example, although workload manager316 is shown as a block separate from group of computer systems 314,workload manager 316 may be implemented in one or more computer systemsin group of computer systems 314.

FIG. 4 illustrates a representative implementation of a workloadmanagement environment, such as described above with respect to FIG. 3.In this example, IBM® Multi-site Workload Lifeline is used to implementthe management environment to load balance TCP/IP workload requestsacross two sites at unlimited distances, when both sites are running thesame server applications and have the same data sources. Although twosites are shown, there may be additional sites. In this example, and aswill be seen, the system preferably defines two (2) tiers of loadbalancing. Generally, a first-tier load balancer registers applicationgroups that contain members that are in both sites. These members areconsidered second-tier load balancers. An external load balancer,operating as a second-tier load balancer, registers groups of serverapplications that are on the same site. As this external load balancerreceives a workload connection request from a first-tier load balancer,the external load balancer distributes the request to one of the serverapplications in the matching application group.

Each workload that is configured to Multi-site Workload Lifeline isclassified as an active/standby or active/query workload. By definition,an active/standby workload can be distributed to only one site at atime, because the workload might contain transactions that updatedatabases. By contrast, an active/query workload can be distributed toboth sites at the same time, because the workload contains onlytransactions that query databases. Multi-site Workload Lifeline enforcesthe single or dual site distribution. If more than one workload isconfigured, some of the workloads can be distributed to one site, someworkloads can be distributed to the other site, and the remainingworkloads can be distributed to both sites.

As seen in FIG. 4, and in a concrete (but non-limiting) example, eachsite 400 is configured as a systems complex or “sysplex.” As iswell-known, a sysplex is a collection of Multiple Virtual Storage (MVS)systems that cooperate, using certain hardware and software products, toprocess work. The sysplex increases the number of processing units andMVS operating systems that can cooperate, which in turn increases theamount of work that can be processed at the site. It uses a standardcommunication mechanism (the cross-system coupling facility, or XCF) forMVS system applications that enables communication between applicationprograms on one or multiple computers. From an architecture standpoint,typically the sysplex is made up of a number of central processorcomplexes (CPCs) that collaborate, through specialized hardware andsoftware, to process a work load. A single CPC comprises a singlecentral processor (CP) and all associated system hardware and software,controlled by a single copy of the operating system (e.g., z/OS). Onetypical operating scenario for a sysplex is where applications runningsimultaneously on separate systems must be able to access the same data,or update a single database, etc., without compromising data integrity.

In this implementation, which is merely representative, a first-tierload balancer 402 determines which site 400 to route a new workloadrequest to, and forwards the request to a second-tier load balancer 404within that site 400. The second-tier load balancer 404 within the sitedetermines which server application 406 within the site to route theworkload request to, and forwards it to the z/OS system 408 where theserver application is running. IBM Multi-site Workload Lifeline acts asa workload manager (to provide the different tiers with routingrecommendations based on the availability and health of the serverapplications and the z/OS systems within the site.

In this particular implementation environment, the workload managerincludes agents 410 and advisors 412 a and 412 b. As illustrated,typically agents 410 execute on each z/OS system 408 in the two sites,and operate to monitor the health of the server applications 406 and thesystem where the agent is active. The agents 410 periodically send thisinformation to the primary advisor 412 a, as indicated by the networkflows labeled 2. The primary advisor 412 a uses this information tocalculate routing recommendations for the workloads that use theseserver applications. The advisor 412 a periodically sendsrecommendations to first-tier load balancers 402 about which site toroute workload requests to, and recommendations to second-tier loadbalancers 404 about which server applications within a site 400 to routethe workload requests to, as indicated by the network flows labeled 1.The primary advisor 412 a also periodically notifies the secondaryadvisor 412 b about any changes in the workload states, indicated by thenetwork flows labeled 3, so that the secondary advisor 412 b can takeover primary advisor responsibilities if the current primary advisor 412a becomes non-operational.

Thus, when workload requests are handled by the first-tier loadbalancers 402, based on routing recommendations from the advisor 412 a,the load balancer 402 selects a site 400 and forwards the request to thesecond-tier load balancer 404 in that site, indicated by the networkflow labeled 4. When workload requests are handled by the second-tierload balancers 404, based on routing recommendations from the advisor412 a, the load balancer 404 selects a server application 406 in thesite and forwards it to the TCP/IP stack 414 running on the z/OS system408, indicated by the network flow labeled 5. When these second-tierload balancers 404 are external, they receive routing recommendationsdirectly from the advisor 412 a. When these second-tier load balancers404 are internal, also known as z/OS sysplex distributors, they resideon a z/OS system 408 in the site, and receive routing recommendationsdirectly by using z/OS Communications Server functions.

In another configuration (not shown), a second-tier load balancer is notresponsible for routing workload requests to a server application withina site. In this case, load balancing within a site is performed by someother node, which is called an intermediary node. Typically, anintermediary node does not communicate directly with the advisor 412 a.It is used in cases where customized load balancing has been built intoa workload. In this type of configuration, the z/OS sysplex distributoris still defined, but it is used only for obtaining recommendations andtopology information that the first-tier load balancer uses to selectthe site for a workload connection request. The intermediary node makesthe load balancing decision to select a server application instancewithin the site.

As explained above, typically a workload comprises one or more groups ofapplications that access the same data sources to provide relatedservices for a client. In this example, preferably all serverapplications in a load balancer application group provide the sameservice for that client, and preferably each server application withinan application group can provide the same services as the otherapplications in the group. The system provides the ability to groupserver applications that access different data sources into their ownworkload to provide more granular control of each group of applications.

In this example embodiment, a site is synonymous with a sysplex.Preferably, all z/OS target systems in a particular site belong to thesame sysplex. In a typical configuration, and as described, thefirst-tier load balancer determines which site to route a new workloadrequest to and forwards the request to a second-tier load balancer. Thesecond-tier load balancer determines which server application within thesite to route the workload request to and forwards it to the z/OS systemwhere the server application is running. Multi-site Workload Lifelineprovides the different tiers with routing recommendations based on theavailability and health of the server applications and the z/OS systemswithin the site.

While the arrangement and techniques in FIG. 4 provide significantadvantages, they are limited to TCP/IP-based connection monitoring andworkload switching of TCP/IP server applications only.

Combining Application and Data Tiers on Different Platforms to Create aWorkload Group

With the above as background, the technique of this disclosure is nowdescribed.

According to this disclosure, different computing system environmenttiers are monitored and combined into a same workload, and loadbalancing decisions are then made based on that information. Inparticular, in this approach both applications and data sources aregrouped into a workload grouping (or “group” or, more generally, a“workload”), and information about both of these tiers is then used todetermine a distribution policy for the workload. In this approach, aload balancer is controlled to route workload connections that aredestined to a site or an alternate site based on the state of theapplication instances and data sharing members in the tiers that aregrouped into the same workload.

In particular, and according to an embodiment of this disclosure,application instances and their data sharing members, even whensupported on tiers in different operating system environments, areassociated together within a same workload group so that these differenttypes of tiers can be monitored to determine their overall suitabilityfor handling workload connection requests directed to the sites.Monitoring agents verify the health, availability and capacity of theresources within each tier, and such information is then used by aworkload manager to create a distribution policy for the workload. Theworkload manager provides the distribution policy to a load balancingmechanism (e.g., a load balancer appliance) that is capable ofdistributing workload connections to either site. The workloadconnections are then routed to one site, or the alternate site.

Thus, the workload herein is based on combining application and datatiers in the same workload and then enabling load balancing decisions tobe made based on that combined workload. In the preferred embodiment,the different tiers are an application tier, and a data tier. This isnot a limitation, as the notion of combining different tiers into a sameworkload can be practiced with other computing system and/or operatingsystem tiers. Such other tiers include, without limitation, a web serverfront-end tier, an application server middleware tier, or the like.Moreover, the approach of combining application and data tiers mayincorporate two or more tiers into the workload.

FIG. 5 illustrates the basic process at a high level. In step 500, theapplication and data tiers are associated into a workload (sometimesreferred to herein as a workload “group” or “grouping”). Thisassociation may be created manually (through an administrativeinterface, by an authorized user), automatically, programmatically, orby some combination of such activities. An application tier typicallyincludes one or more application instances, and a data tier typicallyincludes one or more data sharing members. Data sharing memberstypically comprise data stores, file systems, databases, and the like.The applications and their associated data sharing members typicallyshare common data sources that are mirrored across at least two sitesthat are distinct from one another and typically remote from oneanother. At step 502, monitoring agents determine the availability,health and capacity of the application and data tiers. This informationis then provided to a workload manager, which uses it to create adistribution policy for the workload. This is step 504. At step 506, theworkload manager provides the distribution policy to a load balancer.The load balancer then routes workload connections that are destined forthe site (or its alternative site). This is step 508. Thus, in thedescribed approach, the distinct application and data tiers thatcomprise a same workload are monitored, and the collected information isused by a workload manager to create a distribution policy that thencontrols the routing of workload connections to the sites.

In the context of this disclosure, application instances may access thesame (common) data source (or resource). Each site typically has its owncopy of the data source, but these copies of the data source should notbe accessed at the same time. For example, application instances thatare available at each site may desire to use the same table in adatabase, the same rows in a table in a database, the same file, thesame memory location, or any other suitable types of resources.Generalizing, a data source or resource is any accessible system,device, application, program, process, thread, data store, storage ormemory location, file, object, database, database component, or thelike. Such concurrent access is avoided by the techniques of thisdisclosure.

FIG. 6 illustrates a representative workload management environment inwhich the technique of this disclosure may be practiced. Thisenvironment is not intended to be limiting. As can be seen, and as wasillustrated in FIG. 4, it is assumed that there are two or more sites, apair of which is shown. In particular, a first site is designated 600 a,and a second site is designated 600 b. Typically, sites are locatedremote from one another. As depicted, each site 600 operates anapplication tier 602, and a data tier 604, and each such tier may behosted in a different computing system operating system environment. Arepresentative computing system OS environment may be an IBM z/OS Seriescomputing system, an IBM Linux on System z Series computing system, orsome other. An aspect of this disclosure is that the application tierneed not be hosted on the same computing system OS platform as the datatier. For example, the data tier 604 may be hosted on a mainframe (e.g.,IBM® z/OS) system, while the application tier includes applicationinstances (e.g., web-based applications within an application server)running on IBM Linux on System z (also running on a mainframe). Thisexample scenario, of course, is not intended to be limiting.

The first site 600 a comprises several computing system platforms 608. Aplatform typically comprises hardware, and an operating system. Theapplication tier 602 in the first site 600 a comprises a set ofapplications supported on several computing system platforms. Inparticular, a first computing system platform 608 a supports anapplication instance 606, while a second computing system platform 608 bsupports two additional application instances 606. The data tier 604 inthe first site 600 a comprises a set of data sharing members supportedon several computing system platforms. In particular, a third computingsystem platform 608 c supports two data sharing members 610, while afourth computing platform 608 d supports two additional data sharingmembers 608 as well. The computing system platforms 608 a and 608 b hosta monitoring agent 605, and the computing system platforms 608 c and 608d host a monitoring agent 607. First and third computing systemplatforms 608 a and 608 c may be the same or distinct. Likewise, secondand fourth computing system platforms 608 b and 608 d may be the same ordistinct.

The second site 600 b also comprises several computing system platforms608. Here, the application tier 602 in the second site 600 b comprises aset of applications, once again supported on several computing systemplatforms. In particular, a fifth computing system platform 608 esupports two application instances 606, while a sixth computing systemplatform 608 f also supports two additional application instances 606.The data tier 604 in the second site 600 b also comprises a set of datasharing members supported on several computing system platforms. Inparticular, a seventh computing system platform 608 g supports two datasharing members 608, while an eighth computing platform 608 h supportsone additional data sharing member 608. The computing system platforms608 e and 608 f host the monitoring agent 605, and the computing systemplatforms 608 g and 608 h host the monitoring agent 607. Fifth andseventh computing system platforms 608 e and 608 g may be the same ordistinct. Likewise, sixth and eighth computing system platforms 608 fand 608 h may be the same or distinct.

The architecture of each site shown in FIG. 6 is merely for exemplarypurposes, and it is not intended to be limiting. As noted, variouselements of the computing systems may be integrated or distinct. Inaddition, the monitoring agents 605 and 607 may be distinct orintegrated into a single module.

The operation of the various components is now described. In particular,the monitoring agents 605 in each application tier 602 in each of thesites are configured to monitor the application instances in that tier.In particular, preferably each such monitoring agent determines thehealth, availability and capacity of the application instances to takeon additional work on the computing system wherein the particularmonitoring agent 605 resides. This is depicted by flow “1.” Likewise,the monitoring agents 607 in each data tier 604 in each site areconfigured to monitor the data sharing members of the data source. Inparticular, preferably each such monitoring agent determines the health,availability and capacity of the application instances to take onadditional work on the computing system wherein the particularmonitoring agent 607 resides. This is depicted by flow “2.” Preferably,the respective monitoring agents 605 and 607 report their metrics to theworkload manager 612. This is depicted by flow “3.” Without intending tobe limiting, the monitoring agents provide the workload manager withthese metrics on a defined polling interval (e.g., once every 10seconds), as well as immediately when an unexpected event occurs, suchas an outage to or interruption of an application. The workload managermay poll the monitoring agents, or the agents may push the metrics tothe workload manager. Any request-response protocol may be used for thispurpose.

The workload manager 612 uses this information, as well as additionalavailability information, to signal one or more load balancer appliances615 about how workload connections should be distributed across sites600 a and 600 b. This is depicted by flow “4.” Of course, if there areadditional sites being load-balanced, then the load balancer appliancescontrol the distribution across the multiple sites.

Referring back to FIG. 6, clients 625 desiring access to the workloadeither access the data sources via application tier in the first site600 a, or via the application tier in the second site 600 b. This isdepicted as flow “5.” For client 625 requests for access to theworkload's data sources, the load balancer appliance 615 distributesconnections to an application instance in the application tier 602 inthe site 600 that can best handle the additional workload request (asdefined in a current distribution pattern recommendation provided by theworkload manager). Thus, and based on the metrics collected from themonitoring agents, when the workload manager 612 recommends site 600 aover site 600 b, a load balancer appliance 615 routes a new clientworkload connection request to an application instance in the site 600a. This is depicted by flow “6.” The application instances in site 600 athen query one of the data sharing members in the data tier 604 in site600 a to access the data source. This is depicted by flow “8.” On theother hand, and once again based on the metrics collected from themonitoring agents, when the workload manager 612 recommends site 600 bover site 600 a, the load balancer appliance 615 routes a new clientworkload connection request to an application instance in site 600 b.This is depicted by flow “7.” In this case, the application instances in600 b then queries one of the data sharing members in the data tier insite 600 b to access the data source. This is depicted by flow “9.”

In this example scenario, and as described above, site 600 a has oneless application instance in its application tier than site 600 b, butsite 600 a has one more data sharing member in its data tier than doessite 600 b. As noted above, this information, along with health,availability, and capacity to handle additional work, is used togetherby the workload manager 612 to determine distribution recommendations (a“distribution policy”). For example, assuming that all applicationinstance and data sharing members have the same capacity for handlingnew workload requests, the workload manager 612 might then recommendthat workload connection requests be equally distributed across the twosites. If, however, the business logic performed for this workload bythe application instances on the application tier 602 consume moreresources than accessing the data sources, then the workload manager isable to determine (by using capacity and instances metrics) that thesite with more application instances is better able to handle workloadrequests. In that case, the workload manager would recommend that moreworkload connection requests be distributed to site 600 b than to site600 a. But, when the resulting data source access for this workloadconsumes more resources than performing the business logic on theapplication instances, then the workload manager is able to determine(once again, by using capacity and instances metrics) that the site withmore data sharing members is better able to handle workload requests. Inthat case, the workload manager recommends that more workload connectionrequests be distributed to site 600 a than to site 600 b.

Thus, the distribution policy provided by the workload manager to theload balancer appliance is based at least in part on the capacity of theapplication instances to process additional work relative to thecapacity of the data sharing members to process additional work.

As noted above, the workload manager preferably takes advantage ofadditional availability information in formulating a currentdistribution policy or recommendation. This additional availabilityinformation typically includes a determination of a total number ofavailable application instances and/or data sharing members, as the casemay be. This determination preferably is “dynamic” in the sense that itmay be carried out periodically, continuously, on-demand, or otherwise.Thus, in the context of the example scenario shown in FIG. 6, there arethree (3) application instances and four (4) data sharing membersconfigured in site 600 a, and four (4) application instances and three(3) data sharing members configured in site 600 b. As particularapplication instances or data sharing members (as indicated by themetrics) become unhealthy or unavailable (or as additional instances areconfigured), the determination of the total number of applicationinstances and/or data sharing members then available for servicing theworkload in the workload group varies, and on a dynamic basis.Preferably, and as will be described below, the workload manager 612updates its distribution policy recommendation based on such changes.Generalizing, the workload manager updates its distributionrecommendations synchronously or asynchronously, on-demand, upon changesin the metrics as measured by the monitoring agents, upon changes in thetotal number of available application instances and/or data sharingmembers as calculated by the workload manager, or upon any combinationof such information and measurements.

Thus, the distribution policy (i.e., the workload connection requestpattern) output by the workload manager typically changes, usually in adynamic manner, to take into consideration any and all configuration andoperational changes that are implemented or occurring with respect tothe application instances and data sharing members within the sites.Thus, for example, assume three of the four data sharing members in thefirst site 600 a either are unhealthy or unavailable, then the workloadmanager is able to determine (by using health, availability, andinstances metrics) that the site with more data sharing members isbetter able to handle workload requests. In that case, the workloadmanager recommends that more workload connection requests be distributedto the second site 600 b than to the first site 600 a.

Of course, the above-described scenarios are merely exemplary and shouldnot be taken to limit the scope of this disclosure.

In a representative embodiment, the application tier is hosted by acomputing system executing on a first operating system platform, whilethe data tier is hosted by a computing system executing on a secondoperating system platform. For example, the application tier is hostedon IBM Linux on System z, while the data tier is hosted on z/OS. In thisexample, the monitoring agent for the application tier is implemented bya management agent that executes as a separate Linux on System z gueston a virtual machine (e.g., zVM). The monitoring agent then monitors allof other Linux on System z guests and their applications on that samevirtual machine LPAR. The approach in this example assumes a singleworkload running per Linux on System z guest. Typically, failure of theapplication tier results in a failure of the workload, and this isindependent of the status or availability of the back-end z/OS images inthe site that host the data tier.

The technique of this disclosure provides significant advantages.Foremost, workload groups are defined and enforced with respect toapplications and data, e.g., a logical grouping of application and datatiers into a workload group. The approach enables the workload managerto monitor and control the load balancer to switch workload connectionsfor the workload based on the health, availability and capacity of theapplication instances and data sharing members that comprise theworkload group. The approach as described provides the particularadvantage of enabling workload support across application and data tiersthat reside on different operating system environments. Thus, acustomer's existing investment in mainframe computing resources (e.g.,the data tier) may be maintained, even as the customer migrates orimplements its application front-ends in a different computing systemenvironment. More generally, the approach herein enables a workloadmanager to determine how to provide load balancer appliances withworkload routing recommendations across sites, thereby providingenhanced load balancing.

As has been described, the functionality described above may beimplemented as a standalone approach, e.g., a software-based functionexecuted by a processor, or it may be available as a service (includingas a web service via a SOAP/XML interface). The particular hardware andsoftware implementation details described herein are merely forillustrative purposes are not meant to limit the scope of the describedsubject matter.

More generally, computing devices within the context of the disclosedsubject matter are each a data processing system (such as shown in FIG.2) comprising hardware and software, and these entities communicate withone another over a network, such as the Internet, an intranet, anextranet, a private network, or any other communications medium or link.The applications on the data processing system provide native supportfor Web and other known services and protocols including, withoutlimitation, support for HTTP, FTP, SMTP, SOAP, XML, WSDL, UDDI, andWSFL, among others. Information regarding SOAP, WSDL, UDDI and WSFL isavailable from the World Wide Web Consortium (W3C), which is responsiblefor developing and maintaining these standards; further informationregarding HTTP, FTP, SMTP and XML is available from Internet EngineeringTask Force (IETF). Familiarity with these known standards and protocolsis presumed.

The techniques described herein may be implemented in or in conjunctionwith various server-side architectures including simple n-tierarchitectures, web portals, federated systems, and the like. Thetechniques herein may be practiced in a loosely-coupled server(including a “cloud”-based) environment. An example of the latterenvironment is an Information Technology (IT) infrastructure thatsupports virtualization of resources. An environment of this typetypically comprises host machines (HVs) (e.g., servers or like physicalmachine computing devices) connected to a physical datacenter network,typically via a hypervisor management VLAN. The environment typicallyalso includes load balancers, network data switches (e.g., top-of-rackswitches), firewalls, and the like. Physical servers in the environmentare each adapted to dynamically provide one or more virtual machines(VMs) using virtualization technology. Multiple VMs can be placed into asingle host machine and share the host machine's CPU, memory and otherresources, thereby increasing the utilization of an organization's datacenter. Disparate applications executing within the context of such acloud or virtualized infrastructure may take advantage of the workgroupmanagement technique of this disclosure.

Still more generally, the subject matter described herein can take theform of an entirely hardware embodiment, an entirely software embodimentor an embodiment containing both hardware and software elements. In apreferred embodiment, the trusted platform module function isimplemented in software, which includes but is not limited to firmware,resident software, microcode, and the like. Furthermore, the downloadand delete interfaces and functionality can take the form of a computerprogram product accessible from a computer-usable or computer-readablemedium providing program code for use by or in connection with acomputer or any instruction execution system. For the purposes of thisdescription, a computer-usable or computer readable medium can be anyapparatus that can contain or store the program for use by or inconnection with the instruction execution system, apparatus, or device.The medium can be an electronic, magnetic, optical, electromagnetic,infrared, or a semiconductor system (or apparatus or device). Examplesof a computer-readable medium include a semiconductor or solid statememory, magnetic tape, a removable computer diskette, a random accessmemory (RAM), a read-only memory (ROM), a rigid magnetic disk and anoptical disk. Current examples of optical disks include compactdisk-read only memory (CD-ROM), compact disk-read/write (CD-R/W) andDVD. The computer-readable medium is a tangible, non-transitory item.

The computer program product may be a product having programinstructions (or program code) to implement one or more of the describedfunctions. Those instructions or code may be stored in a non-transitorycomputer readable storage medium in a data processing system after beingdownloaded over a network from a remote data processing system. Or,those instructions or code may be stored in a computer readable storagemedium in a server data processing system and adapted to be downloadedover a network to a remote data processing system for use in a computerreadable storage medium within the remote system.

In a representative embodiment, the interfaces and utility areimplemented in a special purpose computing platform, preferably insoftware executed by one or more processors. The software is maintainedin one or more data stores or memories associated with the one or moreprocessors, and the software may be implemented as one or more computerprograms. Collectively, this special-purpose hardware and softwarecomprises the functionality described above.

While the above describes a particular order of operations performed bycertain embodiments of the invention, it should be understood that suchorder is exemplary, as alternative embodiments may perform theoperations in a different order, combine certain operations, overlapcertain operations, or the like. References in the specification to agiven embodiment indicate that the embodiment described may include aparticular feature, structure, or characteristic, but every embodimentmay not necessarily include the particular feature, structure, orcharacteristic.

Finally, while given components of the system have been describedseparately, one of ordinary skill will appreciate that some of thefunctions may be combined or shared in given instructions, programsequences, code portions, and the like.

The techniques herein generally provide for the above-describedimprovements to a technology or technical field, as well as the specifictechnological improvements to workload management schemes, such asdescribed above.

Having described our invention, what we claim is as follows:
 1. A methodfor providing improved load balancing of workload connection requestsdirected to application instances and data sharing members that are eachsupported in first and second sites, and wherein each of the first andsecond sites has its own copy of the application instances and datasharing members, comprising: associating together, as a combinedworkload group, the application instances and the data sharing members;receiving metrics associated with application instances and the datasharing members that together comprise the combined workload group;dynamically determining a total number of available applicationinstances and data sharing members; generating a distribution policy forworkload connection requests to access the application instances, thedistribution policy being derived from the received metrics and thetotal number of available application instances and data sharing membersdynamically determined; providing the distribution policy to a loadbalancer that has responsibility to select which of the first and secondsites receives a particular workload connection request; and receivingand executing, by the load balancer, the distribution policy, whereinexecution of the distribution policy includes the load balancerreceiving a new workload connection request and delivering the newworkload connection request to one of the first and second sitesaccording to the distribution policy; wherein the application instancesare hosted in an application tier in a first operating systemenvironment, and wherein the data sharing members are hosted in a datatier in a second operating system environment, the first and secondoperating system environments being distinct from one another.
 2. Themethod as described in claim 1 further including: processing the newworkload connection request.
 3. The method as described in claim 1wherein the metrics include information associated with health andavailability of the application instances, together with informationabout a capacity of the application instances to process additionalwork.
 4. The method as described in claim 1 wherein the metrics arereceived on a defined polling interval.
 5. The method as described inclaim 1 wherein the metrics are received in response to an outage orinterruption of an application instance.
 6. The method as described inclaim 3 wherein the metrics include information associated with healthand availability of the data sharing members, together with informationabout a capacity of the data sharing members to process additional work.7. The method as described in claim 6 wherein the distribution policy isbased at least in part on a capacity of the application instances toprocess additional work relative to the capacity of the data sharingmembers to process additional work.
 8. Apparatus for providing improvedload balancing of workload connection requests directed to applicationinstances and data sharing members that are each supported in first andsecond sites, and wherein each of the first and second sites has its owncopy of the application instances and data sharing members, comprising:one or more hardware processors; computer memory holding computerprogram instructions executed by the hardware processors and operativeto: associate together, as a combined workload group, the applicationinstances and the data sharing members; receive metrics associated withapplication instances and the data sharing members that togethercomprise the combined workload group; dynamically determine a totalnumber of available application instances and data sharing members;generate a distribution policy for workload connection requests toaccess the application instances, the distribution policy being derivedfrom the received metrics and the total number of available applicationinstances and data sharing members dynamically determined; provide thedistribution policy to a load balancer that has responsibility to selectwhich of the first and second sites receives a particular workloadconnection request; receive and execute, by the load balancer, thedistribution policy, wherein execution of the distribution policyincludes the load balancer receiving a new workload connection requestand delivering the new workload connection request to one of the firstand second sites according to the distribution policy; wherein theapplication instances are hosted in an application tier in a firstoperating system environment, and wherein the data sharing members arehosted in a data tier in a second operating system environment, thefirst and second operating system environments being distinct from oneanother.
 9. The apparatus as described in claim 8 wherein the computerprogram instructions are further operative to: process the networkworkload connection request.
 10. The apparatus as described in claim 8wherein the metrics include information associated with health andavailability of the application instances, together with informationabout a capacity of the application instances to process additionalwork.
 11. The apparatus as described in claim 8 wherein the metrics arereceived on a defined polling interval.
 12. The apparatus as describedin claim 8 wherein the metrics are received in response to an outage orinterruption of an application instance.
 13. The apparatus as describedin claim 10 wherein the metrics include information associated withhealth and availability of the data sharing members, together withinformation about a capacity of the data sharing members to processadditional work.
 14. The apparatus as described in claim 13 wherein thedistribution policy is based at least in part on a capacity of theapplication instances to process additional work relative to thecapacity of the data sharing members to process additional work.
 15. Acomputer program product in a non-transitory computer readable mediumfor use in a data processing system for providing improved loadbalancing of workload connection requests directed to applicationinstances and data sharing members that are each supported in first andsecond sites, and wherein each of the first and second sites has its owncopy of the application instances and data sharing members, the computerprogram product holding computer program instructions executed by thedata processing system and operative to: associate together, as acombined workload group, the application instances and the data sharingmembers; receive metrics associated with application instances and thedata sharing members that together comprise the combined workload group;dynamically determine a total number of available application instancesand data sharing members; generate a distribution policy for workloadconnection requests to access the application instances, thedistribution policy derived from the received metrics and the totalnumber of available application instances and data sharing membersdynamically determined; provide the distribution policy to a loadbalancer that has responsibility to select which of the first and secondsites receives a particular workload connection request; and receive andexecute, by the load balancer, the distribution policy, whereinexecution of the distribution policy includes the load balancerreceiving a new workload connection request and delivering the newworkload connection request to one of the first and second sitesaccording to the distribution policy; wherein the application instancesare hosted in an application tier in a first operating systemenvironment, and wherein the data sharing members are hosted in a datatier in a second operating system environment, the first and secondoperating system environments being distinct from one another.
 16. Thecomputer program product as described in claim 15 wherein the computerprogram instructions are further operative to: process the networkworkload connection request.
 17. The computer program product asdescribed in claim 15 wherein the metrics include information associatedwith health and availability of the application instances, together withinformation about a capacity of the application instances to processadditional work.
 18. The computer program product as described in claim15 wherein the metrics are received on a defined polling interval. 19.The computer program product as described in claim 15 wherein themetrics are received in response to an outage or interruption of anapplication instance.
 20. The computer program product as described inclaim 17 wherein the metrics include information associated with healthand availability of the data sharing members, together with informationabout a capacity of the data sharing members to process additional work.21. The computer program product as described in claim 20 wherein thedistribution policy is based at least in part on a capacity of theapplication instances to process additional work relative to thecapacity of the data sharing members to process additional work.